On 01/12/2011 06:40 AM, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@xxxxxxxxx>
>
> Since the introduction of the fixes for the
> reorder timer, mac80211 will cause lockdep
> warnings because lockdep confuses
> local->skb_queue and local->rx_skb_queue
> and treats their lock as the same.
>
> However, their locks are different, and are
> valid in different contexts (the former is
> used in IRQ context, the latter in BH only)
> and the only thing to be done is mark the
> former as a different lock class so that
> lockdep can tell the difference.
>
> Reported-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
> Reported-by: Sujith <m.sujith@xxxxxxxxx>
> Reported-by: Miles Lane <miles.lane@xxxxxxxxx>
> Tested-by: Sujith <m.sujith@xxxxxxxxx>
> Tested-by: Johannes Berg <johannes.berg@xxxxxxxxx>
> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
> ---
> net/mac80211/main.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> --- wireless-testing.orig/net/mac80211/main.c 2011-01-12 09:58:07.000000000 +0100
> +++ wireless-testing/net/mac80211/main.c 2011-01-12 10:02:03.000000000 +0100
> @@ -39,6 +39,8 @@ module_param(ieee80211_disable_40mhz_24g
> MODULE_PARM_DESC(ieee80211_disable_40mhz_24ghz,
> "Disable 40MHz support in the 2.4GHz band");
>
> +static struct lock_class_key ieee80211_rx_skb_queue_class;
> +
> void ieee80211_configure_filter(struct ieee80211_local *local)
> {
> u64 mc;
> @@ -569,7 +571,15 @@ struct ieee80211_hw *ieee80211_alloc_hw(
> spin_lock_init(&local->filter_lock);
> spin_lock_init(&local->queue_stop_reason_lock);
>
> - skb_queue_head_init(&local->rx_skb_queue);
> + /*
> + * The rx_skb_queue is only accessed from tasklets,
> + * but other SKB queues are used from within IRQ
> + * context. Therefore, this one needs a different
> + * locking class so our direct, non-irq-safe use of
> + * the queue's lock doesn't throw lockdep warnings.
> + */
> + skb_queue_head_init_class(&local->rx_skb_queue,
> + &ieee80211_rx_skb_queue_class);
>
> INIT_DELAYED_WORK(&local->scan_work, ieee80211_scan_work);
>
>
>
This one works for me. Thanks for sorting this out.
Larry
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